Provisionally add view "repmgr.replication_status"

README.md

@@ -115,8 +115,8 @@ tables:
   - `repmgr.events`: records events of interest
   - `repmgr.nodes`: connection and status information for each server in the
     replication cluster
-  - `repmgr.monitor`: historical standby monitoring information written by `repmgrd`
+  - `repmgr.monitoring_history`: historical standby monitoring information written by `repmgrd`
-     XXX not yet implemented
+
 
 views:
   - `repmgr.show_nodes`: based on the table `repl_nodes`, additionally showing the
@@ -323,6 +323,52 @@ The following replication settings may need to be adjusted:
     # wal_keep_segments = 5000
 
 
+### Monitoring with `repmgrd`
+
+When `repmgrd` is running with the option `monitoring_history=true`, it will
+constantly write standby node status information to the `monitoring_history`
+able, providing a near-real time overview of replication status on all nodes
+in the cluster.
+
+The view `replication_status` shows the most recent state for each node, e.g.:
+
+    repmgr=# SELECT * FROM repmgr.replication_status;
+    -[ RECORD 1 ]-------------+-----------------------------
+    primary_node              | 1
+    standby_node              | 2
+    standby_name              | node2
+    node_type                 | standby
+    active                    | t
+    last_monitor_time         | 2016-01-05 14:02:34.51713+09
+    last_wal_primary_location | 0/3012AF0
+    last_wal_standby_location | 0/3012AF0
+    replication_lag           | 0 bytes
+    replication_time_lag      | 00:00:03.463085
+    apply_lag                 | 0 bytes
+    communication_time_lag    | 00:00:00.955385
+
+The interval in which monitoring history is written is controlled by the
+configuration parameter `monitor_interval_secs`; default is 2.
+
+As this can generate a large amount of monitoring data in the `monitoring_history`
+table , it's advisable to regularly purge historical data with
+`repmgr cluster cleanup`; use the `-k/--keep-history` to specify how
+many day's worth of data should be retained. *XXX not yet implemented*
+
+It's possible to use `repmgrd` to provide monitoring only for some or all
+nodes by setting `failover=manual` in the node's `repmgr.conf` file. In the
+event of the node's upstream failing, no failover action will be taken
+and the node will require manual intervention to be reattached to replication.
+If this occurs, an event notification `standby_disconnect_manual` will be
+created.
+
+Note that when a standby node is not streaming directly from its upstream
+node, e.g. recovering WAL from an archive, `apply_lag` will always appear as
+`0 bytes`.
+
+XXX ALTER TABLE monitoring_history SET UNLOGGED ;
+
+
 
 Reference
 ---------

repmgr--4.0.sql

@@ -1,7 +1,7 @@
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION repmgr" to load this file. \quit
 
-CREATE TABLE nodes (
+CREATE TABLE repmgr.nodes (
   node_id          INTEGER     PRIMARY KEY,
   upstream_node_id INTEGER     NULL REFERENCES nodes (node_id) DEFERRABLE,
   active           BOOLEAN     NOT NULL DEFAULT TRUE,
@@ -15,7 +15,7 @@ CREATE TABLE nodes (
   config_file      TEXT        NOT NULL
 );
 
-CREATE TABLE events (
+CREATE TABLE repmgr.events (
   node_id          INTEGER NOT NULL,
   event            TEXT NOT NULL,
   successful       BOOLEAN NOT NULL DEFAULT TRUE,
@@ -23,7 +23,7 @@ CREATE TABLE events (
   details          TEXT NULL
 );
 
-CREATE TABLE monitoring_history (
+CREATE TABLE repmgr.monitoring_history (
   primary_node_id                INTEGER NOT NULL,
   standby_node_id                INTEGER NOT NULL,
   last_monitor_time              TIMESTAMP WITH TIME ZONE NOT NULL,
@@ -34,9 +34,9 @@ CREATE TABLE monitoring_history (
   apply_lag                      BIGINT NOT NULL
 );
 CREATE INDEX idx_monitoring_history_time
-          ON monitoring_history (last_monitor_time, standby_node_id);
+          ON repmgr.monitoring_history (last_monitor_time, standby_node_id);
 
-CREATE VIEW show_nodes AS
+CREATE VIEW repmgr.show_nodes AS
    SELECT n.node_id,
           n.node_name,
           n.active,
@@ -45,10 +45,30 @@ CREATE VIEW show_nodes AS
           n.type,
           n.priority,
           n.conninfo
-     FROM nodes n
+     FROM repmgr.nodes n
-LEFT JOIN nodes un
+LEFT JOIN repmgr.nodes un
        ON un.node_id = n.upstream_node_id;
 
+-- repmgr.repmgr_get_last_updated()
+CREATE VIEW repmgr.replication_status AS
+  SELECT m.primary_node_id, m.standby_node_id, n.node_name AS standby_name,
+ 	     n.type AS node_type, n.active, last_monitor_time,
+         CASE WHEN n.type='standby' THEN m.last_wal_primary_location ELSE NULL END AS last_wal_primary_location,
+         m.last_wal_standby_location,
+         CASE WHEN n.type='standby' THEN pg_catalog.pg_size_pretty(m.replication_lag) ELSE NULL END AS replication_lag,
+         CASE WHEN n.type='standby' THEN
+           CASE WHEN replication_lag > 0 THEN age(now(), m.last_apply_time) ELSE '0'::INTERVAL END
+           ELSE NULL
+         END AS replication_time_lag,
+         CASE WHEN n.type='standby' THEN pg_catalog.pg_size_pretty(m.apply_lag) ELSE NULL END AS apply_lag,
+         AGE(NOW(), CASE WHEN pg_catalog.pg_is_in_recovery() THEN NOW() ELSE m.last_monitor_time END) AS communication_time_lag
+    FROM repmgr.monitoring_history m
+    JOIN repmgr.nodes n ON m.standby_node_id = n.node_id
+   WHERE (m.standby_node_id, m.last_monitor_time) IN (
+	          SELECT m1.standby_node_id, MAX(m1.last_monitor_time)
+			    FROM repmgr.monitoring_history m1 GROUP BY 1
+         );
+
 /* repmgrd functions */
 
 CREATE FUNCTION request_vote(INT,INT)

repmgr--unpackaged--4.0.sql

@@ -27,7 +27,7 @@ BEGIN
 END$repmgr$;
 
 -- convert "repmgr_$cluster.repl_nodes" to "repmgr.nodes"
-CREATE TABLE nodes (
+CREATE TABLE repmgr.nodes (
   node_id          INTEGER     PRIMARY KEY,
   upstream_node_id INTEGER     NULL REFERENCES repmgr.nodes (node_id) DEFERRABLE,
   active           BOOLEAN     NOT NULL DEFAULT TRUE,
@@ -41,22 +41,22 @@ CREATE TABLE nodes (
   config_file      TEXT        NOT NULL
 );
 
-INSERT INTO nodes
+INSERT INTO repmgr.nodes
   (node_id, upstream_node_id, active, node_name, type, location, priority, conninfo, repluser, slot_name, config_file)
 SELECT id, upstream_node_id, active, name,
        CASE WHEN type = 'master' THEN 'primary' ELSE type END,
        'default', priority, conninfo, 'unknown', slot_name, 'unknown'
-  FROM repl_nodes
+  FROM repmgr.repl_nodes
  ORDER BY id;
 
 
 -- convert "repmgr_$cluster.repl_event" to "event"
 
-ALTER TABLE repl_events RENAME TO events;
+ALTER TABLE repmgr.repl_events RENAME TO repmgr.events;
 
 -- convert "repmgr_$cluster.repl_monitor" to "monitoring_history"
 
-CREATE TABLE monitoring_history (
+CREATE TABLE repmgr.monitoring_history (
   primary_node_id                INTEGER NOT NULL,
   standby_node_id                INTEGER NOT NULL,
   last_monitor_time              TIMESTAMP WITH TIME ZONE NOT NULL,
@@ -67,20 +67,20 @@ CREATE TABLE monitoring_history (
   apply_lag                      BIGINT NOT NULL
 );
 
-INSERT INTO monitoring_history
+INSERT INTO repmgr.monitoring_history
   (primary_node_id, standby_node_id, last_monitor_time,  last_apply_time, last_wal_primary_location, last_wal_standby_location, replication_lag, apply_lag)
 SELECT primary_node_id, standby_node_id, last_monitor_time,  last_apply_time, last_wal_primary_location, last_wal_standby_location, replication_lag, apply_lag
-  FROM repl_monitor;
+  FROM repmgr.repl_monitor;
 
 CREATE INDEX idx_monitoring_history_time
-          ON monitoring_history (last_monitor_time, standby_node_id);
+          ON repmgr.monitoring_history (last_monitor_time, standby_node_id);
 
 
 -- recreate VIEW
 
 DROP VIEW IF EXISTS repl_show_nodes;
 
-CREATE VIEW show_nodes AS
+CREATE VIEW repmgr.show_nodes AS
    SELECT n.node_id,
           n.node_name,
           n.active,
@@ -89,17 +89,17 @@ CREATE VIEW show_nodes AS
           n.type,
           n.priority,
           n.conninfo
-     FROM nodes n
+     FROM repmgr.nodes n
-LEFT JOIN nodes un
+LEFT JOIN repmgr.nodes un
        ON un.node_id = n.upstream_node_id;
 
-DROP VIEW IF EXISTS repl_status;
+DROP VIEW IF EXISTS repmgr.repl_status;
 
--- CREATE VIEW status ... ;
+-- XXX CREATE VIEW repmgr.replication_status ... ;
 
 /* drop old tables */
-DROP TABLE repl_nodes;
+DROP TABLE repmgr.repl_nodes;
-DROP TABLE repl_monitor;
+DROP TABLE repmgr.repl_monitor;
 
 
 /* repmgrd functions */
@@ -139,13 +139,11 @@ CREATE FUNCTION reset_voting_status()
   AS '$libdir/repmgr', 'reset_voting_status'
   LANGUAGE C STRICT;
 
-
 CREATE FUNCTION am_bdr_failover_handler(INT)
   RETURNS BOOL
   AS '$libdir/repmgr', 'am_bdr_failover_handler'
   LANGUAGE C STRICT;
 
-
 CREATE FUNCTION unset_bdr_failover_handler()
   RETURNS VOID
   AS '$libdir/repmgr', 'unset_bdr_failover_handler'